Actuator assembly with manual locking device

Abstract

An actuator assembly for moving a member, such as a gate valve, or the like, between a retracted and extended position, and a locking device for locking the member in its extended position. A ball screw is connected to the member to be moved and is in threaded engagement with a ball nut so that, upon rotation of the ball nut, the ball screw, and therefore the member, moves between a retracted and an extended position. A gear train is connect able between a power source and the ball nut for transferring torque therebetween to rotate the nut member. The locking device cooperates with the actuator for quickly and easily locking the ball screw in an extended position at any time without requiring it to be retracted and then extended, and includes a plunger that moves axially in a housing in response to movement of the ball screw. The plunger has a reduced dimension portion, and a stem is provided that has a reduced dimension portion and a regular dimension portion. The stem is movable in the housing to a first position in which its reduced dimension portion aligns with the reduced dimension portion of the plunger to permit movement of the plunger, and therefore the member, from the predetermined position. The stem is also movable to a second position in which its regular dimension portion aligns with the necked-down portion of the plunger so that the regular dimension portion of the plunger overlaps, and is blocked by, the corresponding regular-dimension of the stem to lock the plunger, and therefore the member, in the predetermined position.

What is claimed is: 
     
       1. A locking device comprising a housing, an armature axially movable in the housing between a retracted and an extended position; a plunger mounted for axial movement in the housing in response to movement of the armature from the retracted position to the extended position; a stem movable in the housing between a first position in which it engages the plunger to lock the plunger, and therefore the armature, in the extended position, and a second position in which axial movement of the plunger, and therefore the armature, is permitted; and a lever adapted to engage the stem to maintain it in its first position, the lever being meltable in response to a predetermined ambient temperature to permit release of the stem and movement of the stem to the second position. 
     
     
       2. The locking device of claim 1 wherein the armature, in its extended position, is adapted to actuate a control module having an axially movable plunger, the plunger extending between the armature and the plunger of the control module so that movement of the armature to its extended position moves the plunger of the control module accordingly and actuates the control module. 
     
     
       3. An actuator assembly for moving a device between a retracted and extended position, the assembly comprising a nut member, a ball screw adapted to be connected to the device, the ball screw being in threaded engagement with the nut member and movable between a retracted and an extended position upon rotation of the nut member, a member for producing torque, a drive assembly adapted to be operatively connected between the torque producing member and the nut member for transferring the torque therebetween to rotate the nut member, and a control system for selectively connecting the drive assembly between the torque producing member and the nut member, the control system comprising an electrical switching device having an armature that moves in response to an input signal, an inner race operatively connected to one of the members, a driver operatively connected to the other member, a wrap spring extending around a portion of the inner race and a portion of the driver, a control module having a plunger which, when moved to a predetermined position, causes the control module to latch to the driver, a locking device having a plunger extending between the armature and the plunger of the control module so that movement of the armature causes corresponding movement of the plungers of the locking device and the control module, the wrap spring being connected to the inner race and to the control module so that, upon actuation of the torque producing member, the inner race, and therefore the wrap spring and the control module, rotate relative to the driver, and, in response to application of the input signal, the control module latches to the driver to tighten the wrap spring around the inner race and the driver to couple the inner race to the driver and transfer the torque from the torque producing member to the nut member to rotate the nut member, the locking device further comprising a stem adapted to be manually moved into engagement with the plunger of the locking device to maintain the plunger of the locking device, and therefore the plunger of the control module in the predetermined position and the control module latched to the driver upon removal of the input signal. 
     
     
       4. The assembly of claim 3 wherein the driver has a bore and wherein the control module extends within the bore and rotates in the bore before application of the input signal. 
     
     
       5. The assembly of claim 4 wherein the control module further comprises at least one latching member, and wherein the movement of the plunger of the control module urges the latching member into engagement with the inner wall of the driver to latch the control module to the driver and therefore tighten the wrap spring around the inner race and the driver to connect the drive assembly between the torque producing member and the nut member. 
     
     
       6. The assembly of claim 5 wherein there are a plurality of latching members in the form of balls, and wherein a plurality of angularly spaced openings are formed in the inner surface of the driver for receiving the balls to latch the control module to the driver. 
     
     
       7. The assembly of claim 3 wherein the plunger of the locking device has a reduced dimension portion and the stem has a reduced dimension portion and a regular dimension portion, the stem being movable to a first position in which its reduced dimension portion aligns with the reduced dimension portion of the plunger to permit movement of the plunger, and therefore the armature, in response to the input signal, the stem being movable to a second position in which its regular dimension portion aligns with the necked-down portion of the plunger so that the regular dimension portion of the plunger overlaps, and is blocked by, the corresponding regular-dimension of the stem to lock the plunger, and therefore the plunger of the control module, in the predetermined latched position. 
     
     
       8. The assembly of claim 7, wherein the armature of the electrical switching device moves from a retracted position to an extended position in response to the input signal, and wherein the plunger of the locking device moves the plunger of the control module in response to the extension of the armature. 
     
     
       9. The assembly of claim 8 further comprising a spring engaging the plunger of the locking device for moving the latter plunger towards the armature when the armature moves from its extended position to its retracted position. 
     
     
       10. The assembly of claim 3 wherein the power source has an output shaft and wherein the drive assembly comprises a plurality of gears connecting the output shaft to the inner race. 
     
     
       11. The assembly of claim 3 further comprising a drive shaft connected to the driver, and a gear connecting the drive shaft to the nut member for rotating the nut member in response to rotation of the driver and therefore the drive shaft. 
     
     
       12. The assembly of claim 3 wherein the inner race is connected to the torque producing member and the driver is connected to the nut member. 
     
     
       13. The assembly of claim 3 further comprising a lever adapted to engage the stem to maintain it in engagement with the plunger of the locking device, the lever being meltable in response to a predetermined ambient temperature to permit release of the stem from the engagement. 
     
     
       14. The assembly of claim 3 wherein the device is a gate valve. 
     
     
       15. A locking device for locking a movable member in a predetermined position, the locking device comprising a housing; a plunger mounted for axial movement in the housing in response to movement of the member, a stem movable in the housing between a first position in which it engages the plunger to lock the plunger, and therefore the member, in the predetermined position, and a second position in which axial movement of the plunger, and therefore the member, is permitted; a lever adapted to engage the stem to maintain it in its first position, the lever being meltable in response to a predetermined ambient temperature to permit release of the stem and movement of the stem to the second position; and a spring disposed in the housing and engaging the plunger for moving the plunger with the member when the member moves from its extended position to its retracted position. 
     
     
       16. A locking device for locking a movable member in a predetermined position, the locking device comprising a housing; a plunger having a reduced dimension portion and a regular dimension portion and being mounted for axial movement in the housing in response to movement of the member; a stem having a reduced dimension portion and a regular dimension portion and being movable in the housing between a first position in which it engages the plunger to lock the plunger, and therefore the member, in the predetermined position, and a second position in which axial movement of the plunger, and therefore the member, is permitted; and a lever adapted to engage the stem to maintain it in its first position, the lever being meltable in response to a predetermined ambient temperature to permit release of the stem and movement of the stem to the second position; wherein, in the first position of the stem, its regular dimension portion aligns with the reduced dimension portion of the plunger so that the regular dimension portion of the plunger overlaps, and is blocked by, the corresponding regular dimension portion of the stem; and wherein, in the second position of the stem, its reduced dimension portion aligns with the reduced dimension portion of the plunger to permit the movement of the plunger.